Little known fact. There are 2Ah coin cell batteries, which are already assembled and tabbed, however, they are really uncommon and hard to find. Also, they are non-rechargeable.
Another option would be a cornell-dubilier RJD3555HPPV30M / 500mA battery, which is a 35x6 mm rechargeable battery, that's as exotic as it gets, at an eye-popping nose-bleeding mouth-watering $40/pop... pew pew pew! cornell-dubilier RJD3555HPPV30M / 500mA is rechargeable. I will order couple to check performance. One very important thing, the power reserve is not the same as the Ah rating, as the cornell-dubilier is a different chemistry and has 25% higher power reserve than the panasonic primary cell, so the cornell-dubilier RJD3555HPPV30M / 500mA is equivalent to about 650mAh Panasonic CR cell. Problem is they require real power management which really complicates the circuit and eats up performance. These are very complex solutions, however, since we are going all out, and I don't care about cost, I might go for it. But then the watch will cost probably between $300 and $500 to make, which I don't care. The problem with the rechargeable i the power density is a lot lower than primaries, but then... rechargeable!